Assessment of ablative margin by MRI with ferucarbotran in radiofrequency ablation for liver cancer: comparison with enhanced CT

OBJECTIVES

Our aim was to determine whether ablated liver parenchyma surrounding a tumour can be assessed by MRI with ferucarbotran administered prior to radiofrequency ablation (RFA) compared with enhanced CT.

METHODS

55 hepatocellular carcinomas (HCCs) in 42 patients and 5 metastatic liver cancers in 3 patients were treated by RFA after ferucarbotran administration. We then performed T(2)* weighted MRI after 1 week and enhanced CT after 1 month. T(2)* weighted MRI demonstrated the ablated parenchyma as a low-intensity rim around the high intensity of the ablated tumour in these cases. The assessment was allocated to one of three grades: margin (+), high-intensity area with continuous low-intensity rim; margin zero, high-intensity area with discontinuous low-intensity rim; and margin (-), high-intensity area extending beyond the low-intensity rim.

RESULTS

Margin (+), margin zero and margin (-) were found in 17, 35 and 5 nodules, respectively. All 17 nodules with margin (+) and 13 of those with margin zero were assessed as having sufficient ablative margins on CT. The remaining 22 nodules with margin zero had insufficient margins on CT. The overall agreement between MRI and CT for the diagnosis of the ablative margin was moderate (κ = 0.507, p < 0.001). No local recurrence was found in 15 HCC nodules with margin (+), whereas local recurrence was found in 4 (11.8%) out of 34 HCC nodules with margin zero.

CONCLUSION

Administration of ferucarbotran before RFA enables the ablative margin to be visualised as a low-intensity rim, and also enables the evaluation of the ablative margin to be made earlier and more easily than with enhanced CT.

Demonstration of cerebral venous variations in the region of the third ventricle on phase-sensitive imaging

BACKGROUND AND PURPOSE

Susceptibility-weighted (SW) MR imaging has enabled noninvasive visualization of the cerebral veins and has shed light on the nature of venous architecture. For successful surgery of the third ventricle, understanding of the anatomy of the subependymal veins of the lateral ventricle and their relationships to the foramen of Monro is required preoperatively. The purpose of this study was to evaluate the anatomic variations of the subependymal veins around the third ventricle by use of phase-sensitive imaging (PSI) on the basis of principles similar to those of SW MR imaging.

MATERIALS AND METHODS

Included in this study were 642 sides in 321 patients. The courses of the anterior septal vein (ASV), thalamostriate vein, and internal cerebral vein (ICV) were evaluated. We classified these into 4 types (IA, IB, IIA, IIB) on the basis of standard classic angiographic criteria. The classification is based on their relationship with the ASV-ICV junction and the presence of a venous angle or a false venous angle, according to the method in a previous study. Other venous variations were classified as type III.

RESULTS

A venous angle was formed in 519 (80.9%), whereas a false venous angle was formed in 123 (19.1%). The ASV-ICV junction was located at the venous angle (type IA) in 407 (63.4%) of 642 sides. In 235 sides (36.6%), the ASV-ICV junction was located posteriorly beyond the foramen of Monro (types IB, IIA, IIB, and III).

CONCLUSIONS

PSI is useful for understanding normal variations of the subependymal veins in the region of the third ventricle.